1. Field of the Invention
The present invention relates generally to hot-pluggable redundant memory systems, and more particularly to the control logic for hot-pluggable redundant memory systems.
2. Description of the Related Art
This section is intended to introduce the reader to various aspects of art which may be related to various aspects of the present invention which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present invention. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
Microprocessor-based systems generally incorporate a plurality of electrical components. Electrical components, such as control chips, processor chips and memory modules, are often mounted on a substrate such as a printed circuit board or a ceramic board. The substrates generally contain conductive traces which allow the electrical components to be electrically coupled to each other via the substrate. Aside from connecting the electrical devices to one another, the substrate often provides a means of routing electrical signals to and from the components on the substrate to other substrates or external components of the system.
For example, a computer system may include dozens of electrical devices, including memory devices. Several memory devices may be disposed on a single printed circuit board thereby creating a memory module such as a Dual Inline Memory Module (DIMM). An array of DIMMs may be electrically coupled to another printed circuit board to create a memory cartridge. A memory cartridge may include a control device to control access to and from the memory devices on the memory cartridge.
A computer system which implements a redundant memory system may include several memory cartridges. Occasionally, when a system is running, one or more of the memory cartridges may fail. Fault tolerant system designs may be particularly advantageous in a computer system. When an uncorrectable fault is detected in a memory device, it may be desirable to change the faulty memory cartridge. Further, it may be desirable to change the memory cartridge without powering down the entire system or disrupting normal operations. However, replacing the bad memory cartridge often requires powering the system down. Additional hurdles are introduced when the memory system is a redundant memory system. Replacing memory cartridges in a redundant memory system while the system is still functioning creates various control issues which may be addressed using a control logic scheme to provide a hot-pluggable redundant memory system.
The present invention may address one or more of the problems set forth above.